Our patient, a 77-year-old male, underwent a medical examination for lower back pain. A careful investigation revealed two large tumors both in his lung and nose. The diagnosis was well-differentiated squamous cell carcinoma by biopsy in both sides. Radiation therapy(36 Gy)was performed on his nasal cavity, and nasal tumor volume was reduced considerably. Because the primary lesion could not be determined we used docetaxel chemotherapy which can be applied for both lung cancer and head and neck cancer. As a result, dissociation of the treatment's effect was seen, and we suspected the presence of overlapping cancer in both lung and nasal cavity. We could not use immunostaining to identify the primary lesion in squamous cell carcinoma as we did for adenocarcinoma. In this case we could infer the presence of overlapping cancer over the course of treatment with chemotherapy.